Configuration Method And Apparatus, And System

ABSTRACT

A configuration method is provided in a communications system. The communications system includes a master node and a secondary node that jointly provide a service for a terminal. The method includes: the secondary node generates configuration information for a signaling radio bearer (SRB), where the SRB is used to transmit a radio resource control (RRC) message between the secondary node and the terminal; and sends the configuration information for the SRB to the master node, so that the configuration information for the SRB is sent to the terminal through the master node. The secondary node receives a result of configuring the SRB by the terminal by using the configuration information for the SRB. In this way, the SRB can be established on the secondary node, and used for RRC message transmission between the secondary node and the terminal, thereby improving efficiency in radio resource management on the secondary node.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application No.PCT/CN2018/079627, filed on Mar. 20, 2018, which claims priority toChinese Patent Application No. 201710179753.7, filed on Mar. 23, 2017.The disclosures of the aforementioned applications are herebyincorporated by reference in their entireties.

TECHNICAL FIELD

This application relates to the field of communications technologies,and in particular, to a configuration method and apparatus, and asystem.

BACKGROUND

In a wireless communications system, considering limited bandwidthresources and coverage of a single cell or base station (or referred toas a node), a service may be provided for a terminal by using radioresources of more than one cell or base station, to better meet capacityand coverage requirements.

When a service is provided for a terminal by using radio resources ofmore than one base station, it is possible that a latency oftransmission between base stations cannot meet a scheduling requirement.Therefore, a dual connectivity (DC) technology is proposed, and hasrelatively good application in a scenario of non-ideal backhaul betweena master base station and a secondary base station.

In a current dual connectivity system, a signaling radio bearer (SRB) isprovided by a master base station, a secondary base station does notprovide an SRB, and all radio resource control (RRC) messages of aterminal are processed by the master base station. This is notbeneficial to improvement in RRC message processing efficiency.

SUMMARY

Embodiments of this application provide a configuration method andapparatus, and a system, in the expectation of establishing an SRB on asecondary node, to implement direct RRC message transmission between thesecondary node and a terminal. This is beneficial to improvement in RRCmessage processing efficiency.

According to an aspect, a configuration method is provided, applied to acommunications system. The communications system includes a master nodeand a secondary node that jointly provide a service for a terminal. Themethod includes: generating, by the secondary node, configurationinformation for a signaling radio bearer (SRB), and sending theconfiguration information for the SRB to the master node, so that theconfiguration information for the SRB is sent to the terminal throughthe master node; and receiving, by the secondary node, a result ofconfiguring the SRB by the terminal by using the configurationinformation for the SRB, where the SRB is used to transmit a radioresource control (RRC) message between the secondary node and theterminal.

According to another aspect, a configuration method is provided, appliedto a communications system. The communications system includes a masternode and a secondary node that jointly provide a service for a terminal.The method includes: receiving, by the terminal, configurationinformation for an SRB of the secondary node from the master node,configuring the SRB by using the configuration information for the SRB,and sending a result of configuring the SRB, where the SRB is used totransmit an RRC message between the secondary node and the terminal.

According to still another aspect, a configuration method is provided,applied to a communications system. The communications system includes amaster node and a secondary node that jointly provide a service for aterminal. The method includes: receiving, by the master node,configuration information for an SRB from the secondary node, andsending the configuration information for the SRB to the terminal; andreceiving, by the master node, a result of configuring the SRB by theterminal by using the configuration information for the SRB, and sendingthe configuration result to the secondary node, where the SRB is used totransmit an RRC message between the secondary node and the terminal.

In the foregoing aspects, the configuration information for the SRB mayalso be referred to as SRB configuration information or direct secondarynode RRC (direct S-RRC) configuration information. The configurationinformation for the SRB (the SRB configuration information or the directS-RRC configuration information) is used to configure the SRB fordirectly transmitting the RRC message between the secondary node and theterminal. That is, the configuration information for the SRB (the SRBconfiguration information or the direct S-RRC configuration information)is used by the terminal to configure the SRB based on the configurationinformation, so that the RRC message is directly transmitted between theterminal and the secondary node. In addition, the configuration resultmay also be referred to as a direct S-RRC configuration result or asecondary node RRC configuration result.

It can be learned that in the foregoing aspects, the configurationinformation for the SRB that is used to transmit the RRC message betweenthe secondary node and the terminal may be sent to the terminal throughthe master node, and after the terminal configures the SRB of thesecondary node, the terminal sends the configuration result to thesecondary node directly or through the master node. In this way, the RRCmessage can be directly transmitted between the secondary node and theterminal, and this is beneficial to improvement in RRC messageprocessing efficiency.

In an implementation, the terminal directly sends the configurationresult to the secondary node, that is, the terminal sends theconfiguration result to the secondary node by using the configured SRB;or the terminal sends the configuration result to the master node, sothat the configuration result is sent to the secondary node through themaster node.

In an implementation, the master node sends first indication informationto the secondary node, where the first indication information is used toinstruct the secondary node to establish the SRB or is used to instructthe secondary node to generate the configuration information for theSRB. The secondary node receives the first indication information, andgenerates the configuration information for the SRB based on the firstindication information. In this way, the secondary node can establishthe SRB based on an instruction of the master node, and this helps themaster node to control establishment of the SRB of the secondary nodebased on a requirement, making it more flexible to control establishmentof the SRB of the secondary node.

Optionally, the first indication information may be carried in anaddition request message sent by the master node to the secondary node,where the addition request message is used to request to add a secondarynode. Alternatively, the first indication information may be carried ina modification request message sent by the master node to the secondarynode, where the modification request message is used to request tomodify a configuration of a secondary node.

In an implementation, the master node sends an addition request messageto the secondary node, where the addition request message is used torequest to add a secondary node. When the secondary node receives theaddition request message from the master node, the secondary nodegenerates the configuration information for the SRB. In this way,information elements transmitted between the master node and thesecondary node can be reduced. When the secondary node is added, the SRBis established on the secondary node by default.

In an implementation, the configuration information for the SRB may bean RRC protocol data unit (PDU), or may be a part of an RRC PDU.

In an implementation, the configuration information for the SRB may besent to the master node after the secondary node performs securityprocessing. In this case, before the secondary node sends theconfiguration information for the SRB to the master node, the secondarynode performs security processing on the configuration information forthe SRB, where the security processing includes integrity protectionand/or encryption. Correspondingly, after the terminal receives theconfiguration information for the SRB, the terminal performs securityprocessing on the configuration information for the SRB, and thenconfigures the SRB of the secondary node by using the configurationinformation for the SRB, where the security processing includesintegrity check and/or decryption.

In an implementation, the configuration information for the SRB includesat least one of the following information: an SRB identifier, a radiolink control (RLC) layer configuration of the SRB, a logical channelconfiguration, and an SRB security parameter. The SRB security parameterincludes, for example, information about a security algorithm and/or aparameter used to derive a security key. The security algorithmincludes, for example, an encryption and/or integrity protectionalgorithm. The information about the security algorithm may beinformation used to indicate the security algorithm, for example, may bean algorithm indication or an algorithm identifier, or may be thesecurity algorithm.

In an implementation, the secondary node may add the configurationinformation for the SRB to an acknowledgment message sent to the masternode. The acknowledgment message is a response message (that is, anaddition request acknowledge message) for the addition request messageused to request to add a secondary node, or a response message (that is,a modification request acknowledge message) for the modification requestmessage used to request to modify a configuration of a secondary node.That is, the foregoing method further includes: receiving, by thesecondary node, an addition request message or a modification requestmessage from the master node; and the sending, by the secondary node,the configuration information for the SRB to the master node includes:sending, by the secondary node, an addition request acknowledge messageor a modification request acknowledge message to the master node, wherethe addition request acknowledge message or the modification requestacknowledge message includes the configuration information for the SRB.

It can be learned that the configuration information for the SRB may besent by the secondary node to the master node in a secondary nodeaddition process (an initial configuration process of dual connectivity)or a secondary node modification process, so that signaling can besaved, and communication efficiency can be improved. When theconfiguration information for the SRB is sent by the secondary node tothe master node in the secondary node modification process, thesecondary node modification process may be triggered by the master node,or may be triggered by the secondary node. When the secondary nodemodification process is triggered by the secondary node, the foregoingmethod further includes: sending, by the secondary node, a modificationrequired message to the master node, where the modification requiredmessage is used to request the master node to allow the RRC message tobe transmitted or the SRB to be established between the secondary nodeand the terminal.

In an implementation, the master node may send the configurationinformation for the SRB of the secondary node to the terminal by usingan RRC connection reconfiguration message of the master node.Correspondingly, the terminal may send the result of configuring the SRBto the master node by using an RRC connection reconfiguration completemessage. That is, the sending, by the master node, the configurationinformation for the SRB of the secondary node to the terminal includes:sending, by the master node, an RRC connection reconfiguration messageto the terminal, where the RRC connection reconfiguration messagecarries the configuration information for the SRB of the secondary node,and the receiving, by the master node, a result of configuring the SRBby the terminal includes: receiving, by the master node, an RRCconnection reconfiguration complete message from the terminal, where theRRC connection reconfiguration complete message carries theconfiguration result. Correspondingly, the receiving, by the terminal,configuration information for an SRB of the secondary node from themaster node includes: receiving, by the terminal, the RRC connectionreconfiguration message from the master node, where the RRC connectionreconfiguration message carries the configuration information for theSRB of the secondary node, and the sending, by the terminal, aconfiguration result to the master node includes: sending, by theterminal, the RRC connection reconfiguration complete message to themaster node, where the RRC connection reconfiguration complete messagecarries the configuration result.

In an implementation, when the terminal sends the configuration resultto the secondary node through the master node, the terminal sends secondindication information to the master node, to indicate a result ofconfiguring the SRB of the secondary node by the terminal. In this way,even when the master node cannot parse the configuration result, themaster node can learn of the result of configuring the SRB of thesecondary node by the terminal.

In an implementation, the master node may send the configurationinformation for the SRB of the secondary node to the terminal by usingan RRC connection reconfiguration message of the master node. An RRCconnection reconfiguration complete message sent by the terminal is aconfiguration result. In this case, when the master node receives theRRC connection reconfiguration complete message, it is considered thatthe configuration succeeds. The RRC connection reconfiguration completemessage may be an RRC connection reconfiguration complete message sentto the master node, or may be an RRC connection reconfiguration completemessage sent to the secondary node.

In an implementation, when the terminal sends the configuration resultto the secondary node through the master node, the master node sends theconfiguration result by using a secondary node reconfiguration completemessage. Optionally, the master node sends a secondary nodereconfiguration complete message to the secondary node, where thesecondary node reconfiguration complete message carries theconfiguration result. Optionally, the master node sends a secondary nodereconfiguration complete message to the secondary node, where thesecondary node reconfiguration complete message is the configurationresult. In this case, when the secondary node receives the secondarynode reconfiguration complete message, it is considered that theconfiguration succeeds.

In an implementation, the master node may parse out the configurationresult, and when the configuration result is successful, send data ofthe terminal to the secondary node or request a core network to senddata of the terminal to the secondary node. Alternatively, the masternode may determine, based on the second indication information, theresult of configuring the SRB of the secondary node by the terminal, andwhen the configuration result is successful, send data of the terminalto the secondary node or request a core network to send data of theterminal to the secondary node.

In an implementation, the master node sends security information usedfor the SRB of the secondary node to the secondary node, where thesecurity information used for the SRB of the secondary node is alsoreferred to as security information for direct S-RRC. The securityinformation includes at least one of the following information: asecurity key and information about a security algorithm. The securityalgorithm includes an encryption algorithm and/or an integrityprotection algorithm. The information about the security algorithm maybe information used to indicate the security algorithm, for example, maybe an algorithm indication or an algorithm identifier, or may be thesecurity algorithm. The secondary node receives the securityinformation, and performs security processing for the SRB based on thesecurity information. The master node may send the security informationto the secondary node before the secondary node generates theconfiguration information for the SRB, that is, before the master nodereceives the configuration information for the SRB of the secondarynode. After the secondary node generates the configuration informationfor the SRB, the secondary node may perform security processing on theconfiguration information for the SRB by using the security information.The security information may be carried in the addition request messageor the modification request message.

In an implementation, the master node sends a key group (also referredto as a key list) to the secondary node, where the key group includes aplurality of keys, so that the secondary node selects a key from the keygroup when updating a key. The secondary node receives the key groupfrom the master node, and selects a key from the key group when updatingthe key. In this way, the secondary node can update the key by itself,thereby further improving configuration efficiency on the secondarynode.

Optionally, the master node may send the key group based on arequirement of the secondary node. To be specific, the secondary nodesends, to the master node, third indication information used to instructthe master node to send the key group.

Optionally, the master node may send a group of count (COUNT) values,that is, a count value group, used to derive the keys in the key groupto the secondary node. The secondary node receives the count valuegroup, and sends a count value used to derive the selected key to theterminal when updating a key, so that the terminal also completessynchronous key update.

Optionally, the master node may send a group of count values, that is, acount value group, used to derive the keys in the key group to theterminal. When the secondary node updates a key, the secondary nodesequentially selects a key from the key group, and instructs theterminal to update the key, that is, sends a notification message to theterminal to instruct the terminal to update the key. When the terminalreceives the notification message, the terminal sequentially selects acount value from the count value group, to perform synchronous keyupdate.

Optionally, the master node sends, to the secondary node, associationinformation between a key in the key group and a count value used toderive the key in the key group. When the secondary node updates a key,the secondary node sends, to the terminal, association informationbetween a selected key and a count value used to derive the key. Theterminal receives the association information, selects the count valuebased on the association information, and performs synchronous keyupdate based on the count value.

In an implementation, after the SRB of the secondary node is configured,the secondary node may directly send an RRC connection reconfigurationmessage to the terminal for configuration. The terminal receives the RRCconnection reconfiguration message, and when reconfigurationcorresponding to the RRC connection reconfiguration message fails,restores configuration before the RRC connection reconfiguration messageis received. Optionally, the terminal may further send a notificationmessage to the secondary node (directly or through the master node), tonotify the secondary node that the RRC connection reconfiguration fails.

In an implementation, the configuration information for the SRB of thesecondary node further includes uplink RRC configuration information,where the uplink RRC configuration information is used to configure amanner in which the terminal sends an uplink RRC message for thesecondary node.

According to still another aspect, this application provides aconfiguration apparatus, including units or means configured to performsteps in any implementation of any one of the foregoing aspects.

According to still another aspect, this application provides aconfiguration apparatus, including at least one processing element andat least one storage element, where the at least one storage element isconfigured to store a program and data, and the at least one processingelement is configured to perform the method provided in anyimplementation of any one of the foregoing aspects.

According to still another aspect, this application provides a computerprogram, where when being run by a processor, the program is used toperform the method in any implementation of any one of the foregoingaspects.

According to still another aspect, a computer readable storage medium isprovided, including the foregoing program.

According to still another aspect, a communications system is provided,including any one of the foregoing configuration apparatuses.

In addition, the embodiments of this application further provide an RRCmessage transmission method and apparatus, and a system, in theexpectation of further improving uplink RRC message transmissionreliability when an SRB can be established on a secondary node.Moreover, the RRC message transmission method and apparatus, and thesystem may be combined with the foregoing configuration method andapparatus, and the foregoing system.

According to an aspect, an RRC message transmission method is provided,applied to a communications system. The communications system includes amaster node and a secondary node that jointly provide a service for aterminal. The method includes: receiving, by the terminal, a downlinkRRC message of the secondary node, where the downlink RRC message isreceived by the master node from the secondary node and sent to theterminal, or the downlink RRC message is sent by the secondary node tothe terminal; and sending, by the terminal, an uplink RRC message, wherethe uplink RRC message is a response message for the downlink RRCmessage, and a path on which the terminal sends the uplink RRC messageis the same as a path on which the terminal receives the downlink RRCmessage. To be specific, when the downlink RRC message is received bythe master node from the secondary node and sent to the terminal, theuplink RRC message is sent by the terminal to the master node, and thensent by the master node to the secondary node. Alternatively, when thedownlink RRC message is sent by the secondary node to the terminal, theuplink RRC message is sent by the terminal to the secondary node. The“sent” herein means being directly sent without being forward by themaster node.

According to another aspect, an RRC message transmission method isprovided, applied to a communications system. The communications systemincludes a master node and a secondary node that jointly provide aservice for a terminal. The method includes: obtaining or generating, bythe master node, uplink RRC configuration information of the secondarynode, where the uplink RRC configuration information is used toconfigure a manner in which the terminal sends an uplink RRC message forthe secondary node; and sending, by the master node, the uplink RRCconfiguration information to the terminal, so that the terminal sendsthe uplink RRC message based on the uplink RRC configurationinformation. The master node may obtain the uplink RRC configurationinformation from the secondary node.

According to still another aspect, an RRC message transmission method isprovided, applied to a communications system. The communications systemincludes a master node and a secondary node that jointly provide aservice for a terminal. The method includes: receiving, by the terminal,uplink RRC configuration information of the secondary node from themaster node, where the uplink RRC configuration information is used toconfigure a manner in which the terminal sends an uplink RRC message forthe secondary node; and sending, by the terminal, the uplink RRC messagefor the secondary node based on the uplink RRC configurationinformation.

In an implementation, the sending manner of the uplink RRC messageincludes: sending, by the terminal, the uplink RRC message for thesecondary node to the secondary node; or sending, by the terminal, theuplink RRC message for the secondary node to the secondary node throughthe master node; or sending, by the terminal, the uplink RRC message forthe secondary node to the secondary node, where the uplink RRC messageis a response message for a downlink RRC message of the secondary node;or sending, by the terminal, the uplink RRC message for the secondarynode to the secondary node through the master node, where the uplink RRCmessage is a response message for a downlink RRC message of thesecondary node; or sending, by the terminal based on a result ofmeasuring a cell of the secondary node, the uplink RRC message for thesecondary node to the secondary node directly or through the masternode; or sending, by the terminal, the uplink RRC message for thesecondary node on a same path as a downlink RRC message of the secondarynode.

Optionally, when the RRC message transmission method is combined withthe foregoing configuration method, the foregoing configurationinformation for the SRB may include the uplink RRC configurationinformation, or both the configuration information for the SRB and theuplink RRC configuration information may be sent to the terminal byusing an RRC connection reconfiguration message of the master node.

Optionally, when the terminal sends, based on the result of measuringthe cell of the secondary node, the uplink RRC message for the secondarynode to the secondary node directly or through the master node, theforegoing uplink RRC configuration information may include a threshold.When a measurement value obtained by the terminal by measuring the cellof the secondary node is greater than the threshold, the terminal sendsthe uplink RRC message for the secondary node to the secondary node.When a measurement value obtained by the terminal by measuring the cellof the secondary node is less than the threshold, the terminal sends theuplink RRC message for the secondary node to the secondary node throughthe master node. When a measurement value obtained by the terminal bymeasuring the cell of the secondary node is equal to the threshold, theterminal may send the uplink RRC message for the secondary node to thesecondary node directly or through the master node.

According to still another aspect, this application provides an RRCmessage transmission apparatus, including units or means configured toperform steps in any implementation of any one of the foregoing aspects.

According to still another aspect, this application provides an RRCmessage transmission apparatus, including at least one processingelement and at least one storage element, where the at least one storageelement is configured to store a program and data, and the at least oneprocessing element is configured to perform the method provided in anyimplementation of any one of the foregoing aspects.

According to still another aspect, this application provides a computerprogram, where when being run by a processor, the program is used toperform the method in any implementation of any one of the foregoingaspects.

According to still another aspect, a computer readable storage medium isprovided, including the foregoing program.

According to still another aspect, a communications system is provided,including any one of the foregoing configuration apparatuses.

It can be learned that in the foregoing aspects, the uplink RRC messagefor the secondary node may be transmitted in a manner configured by themaster node or may be transmitted on a same path as the downlink RRCmessage. In this way, unreliability brought by a plurality of uplink RRCmessage transmission possibilities is alleviated.

In addition, the embodiments of this application further provide aconfiguration method and apparatus, and a system, in the expectation offurther improving mobility management efficiency when an SRB can beestablished on a secondary node. Moreover, the configuration method andapparatus, and the system may be combined with the foregoingconfiguration method and apparatus, and the foregoing system.

According to an aspect, a configuration method is provided, applied to acommunications system. The communications system includes a master node(MN) and a secondary node (SN) that jointly provide a service for aterminal. The method includes the following steps:

receiving, by the secondary node, measurement configuration informationfrom the master node, where the measurement configuration information isused to configure a condition for triggering the secondary node to senda measurement result to the master node;

receiving, by the secondary node from the terminal, a measurement reportobtained by the terminal by measuring a cell of the secondary node; and

when the measurement report includes a measurement result meeting theforegoing condition, sending, by the secondary node, the measurementresult to the master node.

According to another aspect, a configuration method is provided, appliedto a communications system, where the communications system includes anMN and an SN that jointly provide a service for a terminal, and themethod includes the following steps:

sending, by the master node, measurement configuration information tothe secondary node, where the measurement configuration information isused to configure a condition for triggering the secondary node to senda measurement result to the master node; and

receiving, by the master node, a measurement result meeting theforegoing condition from the secondary node, where the measurementresult is obtained by the terminal by measuring a cell of the secondarynode and reported to the secondary node.

In an implementation, the measurement configuration information includesa threshold, and the foregoing condition is that the measurement resultis greater than or equal to the threshold. To be specific, the masternode sends the threshold to the secondary node, the secondary nodereceives the threshold, and when the measurement result is greater thanor equal to the threshold, the secondary node sends the measurementresult to the master node.

In an implementation, the foregoing method further includes:configuring, by the secondary node, the threshold for the terminal. Inthis way, a measurement report reported by the terminal is a measurementreport meeting the threshold requirement, and the secondary node maydirectly send a measurement result in the measurement report to themaster node, without determining whether the measurement result meetsthe threshold requirement.

In an implementation, information sent by the secondary node to themaster node further includes a cell or beam identifier, that is, a cellor beam identifier corresponding to the measurement result meeting thecondition. That is, the foregoing method further includes: sending, bythe secondary node, a cell or beam identifier corresponding to themeasurement result to the master node.

According to still another aspect, this application provides aconfiguration apparatus, including units or means configured to performsteps in any implementation of any one of the foregoing aspects.

According to still another aspect, this application provides aconfiguration apparatus, including at least one processing element andat least one storage element, where the at least one storage element isconfigured to store a program and data, and the at least one processingelement is configured to perform the method provided in anyimplementation of any one of the foregoing aspects.

According to still another aspect, this application provides a computerprogram, where when being run by a processor, the program is used toperform the method in any implementation of any one of the foregoingaspects.

According to still another aspect, a computer readable storage medium isprovided, including the foregoing program.

According to still another aspect, a communications system is provided,including any one of the foregoing configuration apparatuses.

It can be learned that in the foregoing aspects, the master node canconfigure the secondary node to report, in a specific condition, theresult of measuring the cell of the secondary node by the terminal,thereby improving mobility management performance.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram of a dual connectivity scenario accordingto an embodiment of this application;

FIG. 2(a) is a schematic diagram of an LTE-NR dual connectivity scenarioaccording to an embodiment of this application;

FIG. 2(b) is a schematic diagram of another LTE-NR dual connectivityscenario according to an embodiment of this application;

FIG. 2(c) is a schematic diagram of still another LTE-NR dualconnectivity scenario according to an embodiment of this application;

FIG. 3(a) is a schematic architectural diagram of a wireless protocol ofdual connectivity according to an embodiment of this application;

FIG. 3(b) is a schematic architectural diagram of another wirelessprotocol of dual connectivity according to an embodiment of thisapplication;

FIG. 4 is a schematic diagram of an RRC message according to anembodiment of this application;

FIG. 5 is a schematic diagram of a configuration method according to anembodiment of this application;

FIG. 6 is a schematic diagram of a radio bearer establishment methodaccording to an embodiment of this application;

FIG. 7 is a schematic diagram of a configuration method according to anembodiment of this application;

FIG. 8 is a schematic format diagram of a parameter COUNT according toan embodiment of this application;

FIG. 9 is a schematic diagram of an RRC transmission method according toan embodiment of this application;

FIG. 10 is a schematic diagram of another RRC transmission methodaccording to an embodiment of this application;

FIG. 11 is a schematic diagram of a configuration method according to anembodiment of this application;

FIG. 12 is a schematic diagram of an apparatus applied to an SNaccording to an embodiment of this application;

FIG. 13 is a schematic diagram of an apparatus applied to an MNaccording to an embodiment of this application;

FIG. 14 is a schematic diagram of an apparatus applied to a terminalaccording to an embodiment of this application;

FIG. 15 is a schematic structural diagram of a RAN node according to anembodiment of this application; and

FIG. 16 is a schematic structural diagram of a terminal according to anembodiment of this application.

DESCRIPTION OF EMBODIMENTS

The following explains some terms in this application.

(1) A terminal, also referred to as user equipment (UE), is a devicethat provides voice and/or data connectivity for a user, for example, ahandheld device or an in-vehicle device having a wireless connectionfunction. Currently, some terminals are, for example, a mobile phone, atablet computer, a notebook computer, a palmtop computer, a mobileInternet device (MID), and a wearable device such as a smart watch, asmart band, and a pedometer.

(2) A radio access network (RAN) is a part, in a network, that connectsa terminal to a wireless network. A RAN node or device is a node ordevice in the radio access network, and may also be referred to as abase station. Currently, some RAN nodes are, for example, a gNB, atransmission/reception point (TRP), an evolved NodeB (eNB), a radionetwork controller (RNC), a NodeB (NB), a base station controller (BSC),a base transceiver station (BTS), a home base station (for example, Homeevolved NodeB or Home Node B, HNB), a baseband unit (BBU), or a WiFiaccess point (AP). In addition, in a network structure, the RAN mayinclude a centralized unit (CU) node and distributed unit (DU) nodes. Inthis structure, protocol layers of an eNB in Long Term Evolution (LTE)are divided, where functions of some protocol layers are divided to theCU for centralized control, and functions of part or all of remainingprotocol layers are divided to the DUs, which are controlled by the CUin a centralized manner.

(3) The term “plurality of” means two or more than two, and otherquantifiers are similar thereto. The term “and/or” describes anassociation relationship for describing associated objects andrepresents that three relationships may exist. For example, A and/or Bmay represent the following three cases: Only A exists, both A and Bexist, and only B exists. The character “/” generally indicates an “or”relationship between the associated objects.

Referring to FIG. 1, FIG. 1 is a schematic diagram of a dualconnectivity scenario according to an embodiment of this application. Asshown in FIG. 1, a RAN node 110 and a RAN node 120 jointly provide aservice for a terminal 130. The RAN node 110 is a master node (MN). TheRAN node 120 is a secondary node (SN). A control plane connection and auser plane connection exist between the MN 110 and a core network (CN)140. A user plane connection may or may not exist between the SN 120 andthe core network 140. S1-U represents a user plane connection, and S1-Crepresents a control plane connection. When a user plane connection doesnot exist between the SN 120 and the core network 140, data for theterminal 130 may be offloaded from the MN 110 to the SN 120 at a PacketData Convergence Protocol (PDCP) layer. The MN and the SN are alsoreferred to as a master base station and a secondary base station.

Dual connectivity may be implemented between intra-RAT RAN nodes, or maybe implemented between inter-RAT RAN nodes. For example, with evolutionof wireless communications technologies, dual connectivity may beimplemented in a scenario of joint networking of LTE (also referred toas 4G) and New Radio (NR) (also referred to as 5G), and such dualconnectivity is referred to as LTE-NR dual connectivity. In this way, aterminal can obtain radio resources from both LTE and NR air interfacesfor data transmission, thereby obtaining a transmission rate gain.LTE-NR dual connectivity mainly includes the following threearchitectures, which are separately described below with reference toFIG. 2(a), FIG. 2(b), and FIG. 2(c), where an interface between a corenetwork and a RAN node is represented by S1, an interface between RANnodes is represented by X2 (which may also be referred to as an Xninterface). Such a representation form is merely an example, and is notintended to limit this application.

Referring to FIG. 2(a), FIG. 2(a) is a schematic diagram of an LTE-NRdual connectivity scenario according to an embodiment of thisapplication. As shown in FIG. 2(a), an LTE eNB serves as an MN, andcontrol plane and user plane connections may be established for aterminal between the MN and an evolved packet core (EPC) of an LTEsystem. An NR gNB serves as an SN, and a user plane connection may beestablished between the SN and the EPC. It can be learned that in thescenario shown in FIG. 2(a), the LTE eNB is used as an anchor, and theLTE eNB connects to the LTE core network.

Referring to FIG. 2(b), FIG. 2(b) is a schematic diagram of anotherLTE-NR dual connectivity scenario according to an embodiment of thisapplication. A difference from FIG. 2(a) lies in that an NR gNB is usedas an anchor, and the NR gNB connects to an NR core network, which maybe referred to as a next generation core (NGC) or a 5G core network (5thGeneration Core Network, 5G-CN). That is, the NR gNB serves as an MN,and control plane and user plane connections may be established for aterminal between the MN and the NGC. An LTE eNB serves as an SN, and auser plane connection may be established between the SN and the NGC.

Referring to FIG. 2(c), FIG. 2(c) is a schematic diagram of stillanother LTE-NR dual connectivity scenario according to an embodiment ofthis application. Like FIG. 2(a), an LTE eNB is used as an anchor, and adifference from FIG. 2(a) lies in that the LTE eNB connects to an NRcore network NGC. That is, the LTE eNB serves as an MN, and controlplane and user plane connections may be established for a terminalbetween the MN and the NGC. An NR gNB serves as an SN, and a user planeconnection may be established between the SN and the NGC.

In the foregoing three scenarios, the user plane connection may not beestablished between the SN and the core network, and data is transferredthrough the MN. For example, in a downlink direction, data for aterminal reaches the MN first, and the MN offloads the data for theterminal to the SN at a PDCP layer. A form of the offloaded data is, forexample, a PDCP protocol data unit (PDU).

In dual connectivity, a data radio bearer (DRB) may be provided only bythe MN or the SN, or may be provided by both the MN and the SN. When theDRB is provided only by the MN, the DRB is referred to as a master cellgroup (MCG) bearer. When the DRB is provided only by the SN, the DRB isreferred to as a secondary cell group (SCG) bearer. When the DRB isprovided by both the MN and the SN, the DRB is referred to as a splitbearer.

Descriptions are provided below with reference to FIG. 3(a) and FIG.3(b). FIG. 3(a) and FIG. 3(b) are respectively schematic architecturaldiagrams of wireless protocols of dual connectivity according to anembodiment of this application. As shown in FIG. 3(a) and FIG. 3(b),when a bearer is provided only by an MN, that is, a data stream flowsfrom a core network only to the MN, the bearer is an MCG bearer. When abearer is provided only by an SN, that is, a data stream flows from acore network only to the SN, the bearer is an SCG bearer. When a beareris provided by both an MN and an SN, that is, a data stream is offloadedat the MN or the SN, the bearer is a split bearer. For differentiation,a bearer split at the MN may be referred to as an MCG split bearer(shown in FIG. 3(a)), and a bearer split at the SN may be referred to asan SCG split bearer (shown in FIG. 3(b)).

In a current LTE dual connectivity system, a signaling radio bearer(SRB) is provided by an MN, and an SN does not provide an SRB. The SRBis established only between a terminal and the MN for radio resourcecontrol (RRC) message transmission, and all RRC messages of the SN aresent to the terminal through the MN. However, with evolution oftechnologies, the SN is expected to be capable of independentlyproviding an SRB, so that fast RRC configuration can be implemented.Therefore, an RRC message can be transmitted not only between the MN andthe terminal, but also between the SN and the terminal. In this case,three types of RRC messages may exist.

Referring to FIG. 4, FIG. 4 is a schematic diagram of an RRC messageaccording to an embodiment of this application. As shown in FIG. 4, whenan SN can provide an SRB, there are three types of RRC messages: amaster RRC (M-RRC) message, a direct secondary node RRC (direct S-RRC)message, and an embedded secondary node RRC (embedded S-RRC) message.The M-RRC message is used for an MN, and is directly transmitted betweenthe MN and a terminal, that is, directly terminated between the MN andthe terminal. The direct S-RRC message is used for the SN, and isdirectly transmitted between the SN and the terminal. The embedded S-RRCmessage is used for the SN, and the embedded S-RRC message isencapsulated in the M-RRC message, and may be used as an RRC container.The RRC container is an RRC PDU meeting an SN protocol requirement. Itcan be learned that two types of RRC messages, that is, the embeddedS-RRC message and the direct S-RRC message, may be used for the SN.

However, currently, there is no available method for establishing an SRBon an SN. In addition, an RRC message between a terminal and an SN maybe transferred by using an SRB on an MN, or may be directly transferredby using an SRB on the SN, but currently, there is also no availablemethod for selecting a transfer manner of the RRC message between theterminal and the SN.

In view of this, the following embodiment provides a configurationmethod, to establish an SRB on an SN, so that an RRC message can bedirectly transmitted between a terminal and the SN.

Referring to FIG. 5, FIG. 5 is a schematic diagram of a configurationmethod according to an embodiment of this application. As shown in FIG.5, the method includes the following steps.

S510: An SN generates configuration information for an SRB, where theSRB is used to transmit an RRC message between the SN and a terminal.That is, the RRC message may be directly transmitted by the SN to theterminal by using the SRB, without being forwarded by an MN, or the RRCmessage may be directly transmitted by the terminal to the SN by usingthe SRB, without being forwarded by an MN. The configuration informationfor the SRB may also be referred to as SRB configuration information ordirect S-RRC configuration information. A name of the configurationinformation for the SRB is not limited in this application. Theconfiguration information for the SRB (the SRB configuration informationor the direct S-RRC configuration information) is used to configure theSRB for directly transmitting the RRC message between the terminal andthe SN. That is, the configuration information for the SRB (the SRBconfiguration information or the direct S-RRC configuration information)is used by the terminal to configure the SRB based on the configurationinformation, so that the RRC message is directly transmitted between theterminal and the secondary node.

S520: The SN sends the configuration information for the SRB to an MN.

The MN receives the configuration information for the SRB of the SN, andperforms the following operation:

S530: The MN sends the configuration information for the SRB of the SNto the terminal.

The terminal receives the configuration information for the SRB of theSN, and performs the following operation:

S540: The terminal configures the SRB by using the configurationinformation for the SRB of the SN, and sends a configuration result tothe SN. The terminal may send the configuration result to the SN throughthe MN, or may directly send the configuration result to the SN. Then,the terminal may perform step S550 or S570.

S550: The terminal sends the result of configuring the SRB to the MN, sothat the configuration result may be sent to the SN through the MN.

The MN receives the configuration result, and performs the followingstep:

S560: The MN sends the configuration result to the SN.

S570: The terminal sends the configuration result to the SN. That is,the terminal directly sends the result of configuring the SRB of the SNto the SN by using the configured SRB.

In this way, a configuration for the SRB by the SN can be sent to theterminal through the MN, and after the terminal configures the SRB, theterminal sends the configuration result to the SN directly or throughthe MN. In this way, an RRC message can be directly transmitted betweenthe SN and the terminal, and this is beneficial to improvement in RRCmessage processing efficiency.

In step S510, the SN may generate the configuration information for theSRB based on an instruction of the MN, or may generate the configurationinformation for the SRB by default when learning that the MN requests toadd the SN as an SN. That is, before step S510, the foregoing method mayfurther include step S501 or step S502:

S501: The MN sends first indication information to the SN, where thefirst indication information is used to instruct the SN to establish anSRB or is used to instruct the SN to generate configuration informationfor an SRB. The SN receives the first indication information, andgenerates the configuration information for the SRB based on the firstindication information. When the first indication information is used toinstruct the SN to establish the SRB, the SN generates the configurationinformation for the SRB, and sends the configuration information for theSRB to the terminal through the MN, to complete SRB configuration andcomplete SRB establishment. When the first indication information isused to instruct the SN to generate the configuration information forthe SRB, it indicates that the SRB is to be established on the SN;therefore, the SN generates the configuration information for the SRB,and sends the configuration information for the SRB to the terminalthrough the MN, to complete SRB configuration and complete SRBestablishment. In this way, the secondary node can establish the SRBbased on an instruction of the master node, and this helps the masternode to control establishment of the SRB of the secondary node based ona requirement, making it more flexible to control establishment of theSRB of the secondary node.

S502: The SN receives a request message from the MN, where the requestmessage is used to request to add the SN as an SN. The SN receives therequest message, learns that the SN is to be added as an SN, and whenthe SN is added as an SN, establishes an SRB by default, that is,generates configuration information for the SRB by default. That is,when the SN learns that the SN is requested to be added as an SN, the SNmay generate the configuration information for the SRB, without beinginstructed, by the MN by using an information element, to generate theconfiguration information for the SRB. In this way, information elementstransmitted between the MN and the SN can be reduced. When an SN isadded, an SRB is established on the SN by default.

Optionally, the first indication information in step S501 may be carriedin an addition request message sent by the MN to the SN, where theaddition request message is used to request to add an SN. Alternatively,the first indication information may be carried in a modificationrequest message sent by the MN to the SN, where the modification requestmessage is used to request to modify a configuration of a secondarynode. This is further described in a subsequent embodiment, and detailsare not described herein.

In addition, in step S510, the configuration information for the SRBthat is generated by the SN may be an RRC protocol data unit (PDU) or apart of the RRC PDU. For example, if the MN is a RAN node in an LTEsystem and the SN is a RAN node in an NR system, the SN generates an NRRRC PDU, where the NR RRC PDU includes at least the configurationinformation for the SRB of the SN. The NR RRC PDU may be an NR RRCconnection reconfiguration message. In addition, security processing maybe performed on the configuration information for the SRB. For example,the SN performs integrity protection and/or encryption processing on theconfiguration information for the SRB, and then sends the configurationinformation for the SRB to the MN. The MN sends the configurationinformation for the SRB to the terminal. After the terminal receives theconfiguration information for the SRB, the terminal performs integritycheck and/or decryption on the configuration information for the SRB.

The configuration information for the SRB may include at least one ofthe following information: an SRB identifier, a radio link control (RLC)layer configuration of the SRB, a logical channel configuration, and anSRB security parameter. The SRB security parameter may include, forexample, at least one of the following parameters: information about asecurity algorithm and a parameter used to derive a security key. Thesecurity algorithm includes, for example, an encryption and/or integrityprotection algorithm. The information about the security algorithm maybe information used to indicate the security algorithm, for example, maybe an algorithm indication or an algorithm identifier, or may be thesecurity algorithm. Alternatively, the SN may not send the SRB securityparameter, and the terminal and the SN preconfigure security parametersthat maintain consistent. In an optional manner, the SN and the MN use asame security parameter, for example, a same encryption and/or integrityprotection algorithm. Alternatively, the security parameter is sent bythe MN to the terminal, and does not need to be carried in theconfiguration information for the SRB. In addition, content carried inthe security parameter may be partly carried in the configurationinformation for the SRB, and partly preconfigured or sent by the MN tothe terminal.

In step S520, the SN may add the configuration information for the SRBof the SN to an acknowledgment message sent by the SN to the MN, wherethe acknowledgment message is a response message for the additionrequest message used to request to add an SN, or a response message forthe modification request message used to request to modify aconfiguration of an SN. In addition, in step S530, the MN may send theconfiguration information for the SRB of the SN to the terminal by usingan RRC connection reconfiguration message of the MN.

The configuration information for the SRB of the SN may be sent to theMN as an RRC container. The container is, for example, an RRC PDU. Inaddition, the container may be carried in a message sent by the SN tothe MN. After the MN parses out the container from the message, the MNdirectly forwards the container to the terminal without parsing thecontainer. For example, the container is carried in an acknowledgmentmessage sent by the SN to the MN, where the acknowledgment message is aresponse message for the request message used to request to add an SN,or a response message for the modification request message used torequest to modify a configuration of an SN.

In step S540, the terminal generates a corresponding RRC entity and aLayer 2 entity (for example, an RLC entity) based on the configurationinformation for the SRB, and activates security processing for directRRC transmission between the terminal and the SN, to transmit an RRCmessage of the SN. The entities herein are logical entities, and used toimplement RRC and Layer 2 functions. When the configuration informationfor the SRB is carried in the RRC connection reconfiguration message ofthe MN, after the terminal receives the RRC connection reconfigurationmessage of the MN, the terminal extracts the configuration informationfor the SRB from the RRC connection reconfiguration message, and parsesthe configuration information for the SRB by using an RRC format of theSN. If security processing, for example, integrity protection and/orencryption, is performed on the configuration information for the SRB bythe SN, the terminal may perform security processing, for example,integrity check and/or decryption, on the configuration information forthe SRB by using the security parameter.

In step S550, the terminal may add the configuration result to an RRCconnection reconfiguration complete message, and send the RRC connectionreconfiguration complete message to the MN. The configuration result mayalso be referred to as a direct S-RRC configuration result or an SN RRCconfiguration result. For example, the configuration result may besuccessful or failed, to indicate that the result of configuring the SRBof the SN by the terminal is successful or failed. For the configurationresult, the terminal may send second indication information to the MN,where the second indication information is used to indicate theconfiguration result, so that when the MN cannot parse the configurationresult, the MN may learn, based on the second indication information,the result of configuring the SRB of the SN by the terminal. The secondindication information and the configuration result may be carried in asame message sent by the terminal to the MN, for example, carried in theRRC connection reconfiguration complete message sent by the terminal tothe MN.

In addition, the configuration result may be the RRC connectionreconfiguration complete message. For example, when the MN receives theRRC connection reconfiguration complete message, it is considered thatconfiguration of the SRB of the SN (or SN RRC configuration or directS-RRC configuration) succeeds.

In addition, when the RRC connection reconfiguration message carries MNRRC configuration information, the UE separately performs configurationof the MN and configuration of the SN, and returns configuration resultsto the MN by using the RRC connection reconfiguration complete message.

In step S560, the MN may send the configuration result to the SN byusing an SN reconfiguration complete message. In addition, theconfiguration result may be sent to the SN as a container.Alternatively, the SN reconfiguration complete message may be theconfiguration result. When the SN receives the SN reconfigurationcomplete message, it is considered that the configuration succeeds.

Optionally, the MN may parse the configuration result, and only when theconfiguration result is successful, send data for the terminal to the SNor request a core network to send corresponding data to the SN.Alternatively, when the configuration result cannot be parsed by themaster node, for example, the configuration result is sent to the masternode in a form of an RRC container meeting an SN format requirement, themaster node may determine, based on the second indication information,the result of configuring the SRB of the secondary node by the terminal,and when the configuration result is successful, send data for theterminal to the SN or request a core network to send corresponding datato the SN. When the configuration result is failed, the MN may reselectan SN for dual connectivity, or modify the SN, or the MN does not senddata to the SN, and the SN performs reconfiguration by itself. Herein,the data sent by the core network to the SN may be a part or all of thedata for the terminal. That is, whether the core network sends all thedata for the terminal to the SN is not limited. The core network maysend a part of the data to the SN, and send a part of the data to theMN, so that data offloading is completed at the core network.

After the SN receives the result, sent by the MN, of configuring the SRBof the SN by the terminal, if the SN finds that the configuration resultis successful, configuration of the SRB on the SN is completed for theterminal.

In addition, if the SN RRC configuration result is failed, the MN maytrigger an SN release procedure, that is, send an SN release command tothe SN. The SN release command may include indication informationindicating that “SN RRC configuration fails”.

Initial configuration of dual connectivity is completed by the MN, andthe SRB on the SN may be established in an initial configuration processof dual connectivity. A description is provided below with reference toan accompanying drawing.

Referring to FIG. 6, FIG. 6 is a schematic diagram of a radio bearerestablishment method according to an embodiment of this application. Asshown in FIG. 6, the method includes the following steps.

S610: A RAN node 110 sends an addition request message to a RAN node120, where the addition request message is used to request to add theRAN node 120 as an SN.

Optionally, the addition request message may carry the first indicationinformation in the foregoing embodiment, to instruct the RAN node 120 toestablish an SRB or generate configuration information for an SRB.Alternatively, the addition request message may not carry the firstindication information, but instead when the RAN node 120 receives theaddition request message, the RAN node 120 establishes an SRB bydefault, to generate configuration information for the SRB by default.

After the RAN node 120 receives the addition request message, the RANnode 120 learns that the RAN node 110 is to add the RAN node 120 as anSN, and then performs SCG configuration. In this embodiment, in aprocess in which the RAN node 120 performs SCG configuration, the RANnode 120 generates SCG configuration information, and sends thegenerated SCG configuration information to the RAN node 110, where theSCG configuration information carries the configuration information forthe SRB (or direct S-RRC configuration information). That is, the RANnode 120 performs the following steps:

S620: The RAN node 120 generates configuration information for an SRB.

S630: The RAN node 120 adds the generated configuration information forthe SRB to an addition request acknowledge message, and sends theaddition request acknowledge message to the RAN node 110, where theaddition request acknowledge message is a response message for theaddition request message.

Like the foregoing embodiment, the configuration information for the SRBof the SN may be carried as a container in the addition requestacknowledge message sent to the MN. For example, the configurationinformation for the SRB may be sent to the MN as an RRC PDU of the SN ora part of the RRC PDU.

The RAN node 110 receives the addition request acknowledge message sentby the RAN node 120, and performs the following operation:

S640: The RAN node 110 adds the configuration information for the SRB ofthe RAN node 120 to an RRC connection reconfiguration message, and sendsthe RRC connection reconfiguration message to a terminal.

For example, if the MN is a RAN node in LTE and the SN is a RAN node inNR, the MN sends an LTE RRC connection reconfiguration message to theterminal. The LTE RRC connection reconfiguration message includes theconfiguration information for the SRB of the SN, for example, includesthe RRC PDU of the SN, that is, the MN forwards the RRC PDU of the SN tothe terminal. Even when the configuration information for the SRB of theSN is a part of the RRC PDU, the MN can still forward the complete RRCPDU to the terminal, to send the configuration information for the SRBof the SN to the terminal.

After the terminal receives the RRC connection reconfiguration message,the terminal parses out the configuration information for the SRB of theRAN node 120 from the RRC connection reconfiguration message, andperforms the following operations:

S650: The terminal configures the SRB of the RAN node 120 by using theconfiguration information for the SRB of the RAN node 120, for example,establishes an RRC entity and a Layer 2 entity, and activates securityprocessing for direct RRC transmission between the terminal and the SN,to generate an RRC connection reconfiguration complete message. Thisprocess is a process of adding the SRB by the terminal, and includesestablishing a PDCP instance by using a security configuration of theSN, establishing an RLC instance based on an RLC configuration,establishing a logical channel based on a logical channel configuration,and the like. The instance is a logical unit, and used to perform anoperation meeting a PDCP or RLC layer protocol. Then, step S660 isperformed.

S660: The terminal adds a result of configuring the SRB of the RAN node120 to an RRC connection reconfiguration complete message, and sends theRRC connection reconfiguration complete message to the RAN node 110.

When the RRC connection reconfiguration message sent by the RAN node 110includes configuration information of the MN, the terminal separatelyperforms configuration of the MN and configuration of the SN. Theconfiguration of the MN is performed based on the configurationinformation of the MN in the RRC connection reconfiguration message, andmay include configuration of an SRB and/or a DRB or the like of the MN.The configuration of the SN is performed based on configurationinformation of the SN in the RRC connection reconfiguration message, andincludes configuration of the SRB of the SN. When configuration iscompleted, the terminal may send MN and SN configuration results to theMN by using the RRC connection reconfiguration complete message.

Optionally, for the SN configuration result, the terminal may add theforegoing second indication information to the RRC connectionreconfiguration complete message, to indicate the result of configuringthe SRB of the SN by the terminal.

The RAN node 110 receives the RRC connection reconfiguration completemessage, parses out the result of configuring the SRB of the SN by theterminal from the RRC connection reconfiguration complete message, andperforms the following step:

S670: The RAN node 110 sends the configuration result to the RAN node120. The RAN node 110 may send the configuration result to the RAN node120 by using an SN reconfiguration complete message.

Optionally, the RAN node 110 may send the configuration result to theRAN node 120 in a form of a container. In addition, optionally, the RANnode 110 may parse the configuration result, and only when theconfiguration result is successful, send data for the terminal to theRAN node 120, that is, the SN, or request a core network to send datafor the terminal to the SN.

In this way, the SRB is established on the SN for the terminal.

It can be learned that the method shown in FIG. 5 may be completed in aninitial configuration process of dual connectivity. The configurationinformation for the SRB of the SN is sent to the MN by using theaddition request acknowledge message, and sent to the terminal by usingthe RRC connection reconfiguration message of the MN. Then, the terminalconfigures the SRB of the SN by using the configuration information forthe SRB of the SN, and sends the configuration result to the MN by usingthe RRC connection reconfiguration complete message. The MN sends theconfiguration result to the SN by using the SN reconfiguration completemessage. In this way, when initial configuration of dual connectivity iscompleted, the SRB is established on the SN at the same time, therebysaving signaling and improving communication efficiency.

In addition, the RRC connection reconfiguration complete message may bethe configuration result, and is sent by the terminal to the MN whenconfiguration succeeds. In addition, the SN reconfiguration completemessage may be the configuration result, and is sent by the MN to the SNwhen configuration succeeds.

In the embodiment shown in FIG. 6, the SRB on the SN is configured inthe initial configuration process of dual connectivity. In anotherembodiment, an SRB on an SN may be separately configured. For example,only a DRB on the SN may be configured in an initial configurationprocess of dual connectivity, and in a DC process, an MN or the SNtriggers configuration or establishment of the SRB. In addition, the SRBon the SN may be configured in another configuration process, forexample, in an SN modification process. A description is provided belowwith reference to FIG. 7.

Referring to FIG. 7, FIG. 7 is a schematic diagram of a configurationmethod according to an embodiment of this application. As shown in FIG.7, the method includes the following steps.

S710: An MN sends a modification request message to an SN, where themodification request message is used to request to modify aconfiguration of an SN, for example, request to establish some bearerson the SN, or request to modify an SCG bearer or an SCG part of a splitbearer, or request to add or release an SCG cell. In this embodiment,the SN is requested to generate configuration information for an SRB,and allocate a corresponding radio resource.

Optionally, the modification request message may carry the firstindication information in the foregoing embodiment, to instruct the SNto establish the SRB or generate the configuration information for theSRB.

After the SN receives the modification request message, the SN parsesout the first indication information, and performs SCG configurationbased on the first indication information. In this embodiment, in aprocess in which the SN performs SCG configuration, the SN generates SCGconfiguration information, and sends the generated SCG configurationinformation to the MN. The SCG configuration information carries theconfiguration information for the SRB (or direct S-RRC configurationinformation). That is, the SN performs the following steps:

S720: The SN generates configuration information for an SRB.

S730: The SN adds the generated configuration information for the SRB toa modification request acknowledge message, and sends the modificationrequest acknowledge message to the MN. The modification requestacknowledge message is a response message for the modification requestmessage.

A form or content of the configuration information for the SRB of the SNis the same as that in the foregoing embodiment, and details are notdescribed herein again.

The MN receives the modification request acknowledge message sent by theSN, and performs steps S740 to S760. Steps S740 to S760 are similar tosteps S640 to S660 in FIG. 6, and details are not described hereinagain.

In step S760, the MN receives an RRC connection reconfiguration completemessage, parses out a result of configuring the SRB of the SN by theterminal from the RRC connection reconfiguration complete message, andperforms the following step:

S770: The MN sends the configuration result to the SN, where the MN maysend the configuration result to the SN by using an SN modificationconfirm message.

Optionally, the MN may send the configuration result to the SN in a formof a container. In addition, optionally, the MN may parse theconfiguration result, and only when the configuration result issuccessful, send data for the terminal to the SN or request a corenetwork to send data for the terminal to the SN.

In this way, the SRB is established on the SN for the terminal.

The foregoing SN modification is triggered by the MN. Optionally, the SNmodification may be triggered by the SN. In this case, different fromthe foregoing embodiment, before step S710, the method may furtherinclude step S701: The SN sends a modification required message to theMN, where the modification required message is used to request the MN toallow the SRB to be established between the SN and the terminal or allowan RRC message to be transmitted between the SN and the terminal.

Optionally, the modification required message carries indicationinformation, where the indication information is used to instruct the MNto send security information used for the SRB of the SN to the SN.

The security information is described in detail in the followingembodiment, and details are not described herein.

It can be learned that the method shown in FIG. 5 may be completed indual connectivity, for example, in an SN modification process. Theconfiguration information for the SRB of the SN is sent to the MN byusing the modification request acknowledge message, and sent to theterminal by using the RRC connection reconfiguration message of the MN.Then, the terminal configures the SRB of the SN by using theconfiguration information for the SRB of the SN, and sends theconfiguration result to the MN by using the RRC connectionreconfiguration complete message. The MN sends the configuration resultto the SN by using the SN modification confirm message. In this way,when an SN modification of dual connectivity is completed, the SRB isestablished on the SN at the same time, thereby saving signaling andimproving communication efficiency.

In the foregoing embodiments, the MN may further send securityinformation used for the SRB of the SN (or referred to as securityinformation for direct S-RRC) to the SN. The security informationincludes at least one of the following: a security key and informationabout a security algorithm. The security algorithm includes anencryption algorithm and/or an integrity protection algorithm. Theinformation about the security algorithm may be information used toindicate the security algorithm, for example, may be an algorithmindication or an algorithm identifier, or may be the security algorithm.In this way, the SN may perform security processing for the SRB of theSN by using the security information, for example, performencryption/decryption or integrity protection/integrity check. The MNmay send the security information to the SN before the SN generates theconfiguration information for the SRB, that is, before the MN receivesthe configuration information for the SRB of the SN. After the SNgenerates the configuration information for the SRB, the SN may performsecurity processing on the configuration information for the SRB byusing the security information, for example, perform integrityprotection and/or encryption. If the SRB on the SN is established in aninitial configuration process of dual connectivity, the securityinformation may be carried in the addition request message in step S610.If the SRB on the SN is established in a dual connectivity process, thesecurity information may be carried in the modification request messagein step S710.

Currently, in an MCG split bearer configuration process, the MN does notsend the security information to the SN. Because the MN offloads a PDCPdata packet to the SN at a PDCP layer, and encryption is completed atthe PDCP layer, the SN does not need to encrypt data again. However, inthis embodiment, the MN may send the security information to the SN inany scenario, so that the SN performs security processing for the SRB.To be specific, in the MCG split bearer configuration process, that is,when the MN offloads data for the terminal to the SN at the PDCP layer,the MN still sends the security information to the SN.

The security key may be derived based on an access stratum (AS) root key(for example, KeNB) of the MN. For example, when the MN is a RAN node inan LTE system, the security key may be SKeNB derived based on KeNB. TheSN selects an encryption/decryption algorithm and an integrityprotection/check algorithm according to a local policy. The SN derives,based on the selected algorithms and the security key, a key forencryption/decryption and a key for integrity protection/check, tocomplete encryption/decryption and integrity protection/check onsignaling and data packets carried on the SRB and the DRB. In the LTEsystem, an initial AS root key is KeNB. A core network device generatesKeNB based on a root key KASME and a non-access stratum (NAS) uplinkcount, and sends the generated KeNB to the RAN node for the RAN node tocalculate an AS security key. The RAN node may derive SKeNB based onKeNB and a parameter COUNT, and send SKeNB to the SN. Referring to FIG.8, FIG. 8 is a schematic format diagram of a parameter COUNT accordingto an embodiment of this application. As shown in FIG. 8, the parameterCOUNT includes two parts: a high-order hyper frame number (HFN) and alow-order PDCP sequence number (PDCP SN).

Representation forms of an AS root key and a derived key of the AS rootkey are described above by using those in the LTE system as an example,but are not limited in this application. For example, when the MN is abase station in the LTE system, the AS root key and the derived key ofthe AS root key are represented as KeNB and SKeNB. When the MN is a basestation in a system of another standard, a different form may be usedfor representation. For example, in a 5G communications system, the ASroot key and the derived key of the AS root key may be represented asKgNB and SKgNB, or Kcu and SKcu. Certainly, other representation formsmay also be used, and are not enumerated herein, and this application isnot limited to the representation forms.

After dual connectivity is configured for the terminal, serving cellgroups are divided into an MCG and an SCG. A cell in the MCG belongs tothe MN, and a cell in the SCG belongs to the SN. Carrier aggregation(CA) may be configured in the MCG and/or the SCG In CA of the SCG anuplink component carrier (CC) is configured for at least one cell,including a primary secondary cell (PSCell), and a physical uplinkcontrol channel (PUCCH) resource is configured for the PSCell.

Currently, the PSCell can be changed only when the SCG is changed, thatis, a PSCell change is accompanied by key change and random accessprocesses. However, when the SRB is established on the SN, the SRBexists between the terminal and the SN, and independent measurement canbe implemented on an SN side. For example, the SN performs measurementconfiguration on the terminal by using an RRC message, and the terminalperforms measurement and reporting accordingly. In this case, the SN maytrigger a PSCell change by itself, and the PSCell change is accompaniedby key update.

Based on this, in an embodiment, the SN may send a request message tothe MN, and then the MN sends an updated key to the SN and the terminal,where the request message is used to request the updated key from theMN. This process causes a specific latency.

As the SRB can be established on the SN, configuration can be directlyperformed between the SN and the terminal. In this way, fastconfiguration can be implemented. Further, if the SN can update a key byitself, configuration efficiency on the SN can be further improved.

Based on this, in another embodiment, the MN may send a key group (or akey list) to the SN for the SN to select a key from the key group whenupdating a key. Optionally, the key group may be carried in the requestmessage in step S502 in FIG. 5, or the addition request message in stepS610 in FIG. 6, or the modification request message in step S710 in FIG.7. In addition, the MN may send the key group based on an instruction ofthe SN. For example, the SN sends indication information to the MN, toinstruct the MN to send the key group to the SN. The indicationinformation may be separately sent, or may be carried in anothermessage. For example, in step S701 in FIG. 7, the SN may send theindication information to the MN. Certainly, the MN may not need to sendthe key group based on an instruction of the SN, but actively triggersending of the key group.

In an implementation, the MN sends, to the SN, the key group and a groupof count (COUNT) values, that is, a count value group (or referred to asa count value list, COUNT list) used to derive keys in the key group.The SN receives the key group and the count value group, and selects anew key, that is, a key different from an existing key, from the keygroup when a key needs to be updated. Then, the SN sends a count valueused to derive the key to the terminal, so that the terminal completessynchronous key update.

The SN may sequentially or randomly select the key. When the SNsequentially selects the key, the MN may not send the count value groupto the SN, and send the count value group to the terminal. When the SNupdates the key, the SN sends notification information to the terminal,to instruct the terminal to update the key, and the terminalsequentially uses a count value for synchronous key update.Alternatively, association information may be set for a key and a countvalue used to derive the key, to associate the key with the count value.For example, a same sequence number is set for the key and the countvalue. When the SN randomly selects the key, association information ofthe selected key is sent to the terminal, so that the terminalaccordingly selects the corresponding count value for synchronous keyupdate.

The key herein is a derived key, derived from a root key and a countvalue. A description about the key is the same as that in the foregoingembodiment, and details are not described herein again.

In addition, in the foregoing embodiments, when the terminal performs MNRRC configuration, but cannot perform SN SRB configuration (or RRCconfiguration or direct S-RRC configuration), the terminal may send SNSRB configuration failure information to the MN. In addition, theterminal may send an RRC connection re-establishment request message tothe SN, where the RRC connection re-establishment request message may becarried in the RRC connection reconfiguration complete message sent tothe MN. After the MN receives the RRC connection reconfigurationcomplete message, the MN sends a modification request message to the SN,and adds the RRC connection re-establishment request message to themodification request message.

After the SN SRB configuration is completed, the SN may directly send anRRC connection reconfiguration message to the terminal forconfiguration. When the terminal cannot perform the RRC configuration,the terminal triggers an RRC connection re-establishment process betweenthe terminal and the SN according to the prior art, but the processinterrupts transmission of data carried on the SN. In view of thisproblem, in an embodiment of this application, the terminal restoresconfiguration before the RRC connection reconfiguration message isreceived, that is, works based on the configuration before the RRCconnection reconfiguration message is received, does not trigger RRCconnection re-establishment, and notifies the SN that latestconfiguration fails. The terminal may notify, directly or through theMN, the SN that latest configuration fails.

Still referring to FIG. 4, when the SRB is established on the SN totransmit an RRC message between the SN and the terminal, RRC messagesbetween the terminal and a RAN may include an RRC message of the MN(that is, an M-RRC message) and an RRC message of the SN (that is, anS-RRC message). A downlink S-RRC message (that is, an RRC message sentby the SN to the terminal) includes a direct S-RRC message and anembedded S-RRC message. An RRC message (for example, an RRC connectionreconfiguration message) that is not related to negotiation between theSN and the MN may be directly sent by the SN to the terminal, or may besent to the terminal through the MN. That is, an RRC message of a directS-RRC type may be used, or an RRC message of an embedded S-RRC type maybe used. A specific manner or message to be used may be determined bythe SN.

There are also two possibilities for sending an uplink S-RRC message.That is, the uplink S-RRC messages (that is, RRC messages sent by theterminal to the SN) includes a direct S-RRC message and an embeddedS-RRC message. When the terminal uses both the direct S-RRC message andthe embedded S-RRC message, a network side problem may be caused. Forexample, uplink RRC message transmission reliability decreases. Forexample, after the terminal sends a measurement report by using theembedded S-RRC message, the terminal sends, in a short time, anothermeasurement report by using the direct S-RRC message. However, due to anair interface latency of the MN and a latency of an interface betweenthe MN and the SN, the measurement report sent by using the embeddedS-RRC message may reach the SN later than the measurement report sent byusing the direct S-RRC message. Consequently, the SN cannot use themeasurement result.

In view of this, the embodiments of this application provide thefollowing RRC message transmission methods, to improve the uplink RRCmessage transmission reliability.

In a first method, uplink and downlink paths are the same. This methodis applicable to a case in which an uplink RRC message for an SN that issent by a terminal is a response message for a downlink RRC message ofthe SN. For example, an RRC connection reconfiguration complete messageis a response message for an RRC connection reconfiguration message. Inthis case, the terminal sends the uplink RRC message on a same path asthe downlink RRC message.

Referring to FIG. 9, FIG. 9 is a schematic diagram of an RRCtransmission method according to an embodiment of this application. Asshown in FIG. 9, the method is applied to a communications system, wherethe communications system includes an MN and an SN that jointly providea service for a terminal, and the method includes the following steps:

S910: The terminal receives a downlink RRC message of the SN, where thedownlink RRC message is received by the MN from the SN and sent to theterminal (a path shown by a dashed line in the figure), or the downlinkRRC message is sent by the SN to the terminal (a path shown by a solidline in the figure).

S920: The terminal sends an uplink RRC message, where the uplink RRCmessage is a response message for the downlink RRC message, and a pathon which the terminal sends the uplink RRC message is the same as a pathon which the terminal receives the downlink RRC message. To be specific,when the downlink RRC message is received by the MN from the SN and sentto the terminal, the uplink RRC message is sent by the terminal to theMN and sent by the MN to the SN (a path shown by a dashed line in thefigure). Alternatively, when the downlink RRC message is sent by the SNto the terminal, the uplink RRC message is sent by the terminal to theSN (a path shown by a solid line in the figure). The “sent” herein meansbeing directly sent without being forwarded by the MN.

It can be learned that the terminal sends the uplink RRC message on apath consistent with a path on which the downlink RRC message of the SNis received. In this way, a problem of poor uplink RRC messagereliability caused by sending on two paths is resolved.

In a second method, an MN or an SN configures an uplink RRC transmissionpath. This method may be applied to a case in which a terminal initiatesan uplink RRC message, and may also be applied to a case in which anuplink RRC message for an SN that is sent by a terminal is a responsemessage for a downlink RRC message of the SN.

For example, an MN configures an uplink RRC transmission path. Referringto FIG. 10, FIG. 10 is a schematic diagram of another RRC transmissionmethod according to an embodiment of this application. As shown in FIG.10, the method is applied to a communications system, where thecommunications system includes an MN and an SN that jointly provide aservice for a terminal, and the method includes the following steps.

S1010: The MN generates uplink RRC configuration information of the SN,where the uplink RRC configuration information is used to configure amanner in which the terminal sends an uplink RRC message for the SN.

S1020: The MN sends the uplink RRC configuration information to theterminal, so that the terminal sends the uplink RRC message based on theuplink RRC configuration information.

The terminal receives the uplink RRC configuration information, andperforms the following step:

S1030: The terminal sends an uplink RRC message for the SN based on theuplink RRC configuration information.

The uplink RRC configuration information may be sent to the terminal inthe process shown in FIG. 5 of establishing the SRB of the secondarynode, or may be sent to the terminal after the process shown in FIG. 5of establishing the SRB of the secondary node, that is, after the SRB ofthe secondary node is established, and the MN may add the uplink RRCconfiguration information to an RRC connection reconfiguration message.

Alternatively, an SN may configure an uplink RRC transmission path, thatis, the sending manner of the uplink RRC message may be configured bythe SN. In this case, step S1010 may be: obtaining, by the MN, uplinkRRC configuration information of the SN. Optionally, the uplink RRCconfiguration information may be included in the foregoing configurationinformation for the SRB. In addition, possible configurations in theuplink RRC configuration information include:

1. A response message (or referred to as a reply message) for an RRCmessage sent by the SN is directly sent to the SN. That is, the terminaldirectly sends an uplink RRC message for the SN to the SN, where theuplink RRC message is a response message for a downlink RRC message ofthe SN.

2. A response message (or referred to as a reply message) for an RRCmessage sent by the SN is sent to the SN through the MN. That is, theterminal directly sends an uplink RRC message for the SN to the MN, andthe MN sends the uplink RRC message for the SN to the SN, where theuplink RRC message is a response message for a downlink RRC message ofthe SN. In this case, the terminal sends, to the MN, an RRC message in aformat of a standard to which the MN belongs, that is, an M-RRC message.The M-RRC message includes an RRC message that is returned by theterminal to the SN and that is in a format of a standard to which the SNbelongs, that is, an embedded S-RRC message. For example, if the MN isan LTE eNB and the SN is an NR gNB, after the SN sends an NR RRCconnection reconfiguration message to the UE, the terminal generates anNR RRC connection reconfiguration complete message after theconfiguration. The NR RRC connection reconfiguration complete message issent to the MN by using an LTE RRC message, and then sent by the MN tothe SN.

3. The terminal sends, based on a result of measuring a cell of the SN,an uplink RRC message for the SN to the SN directly or through the MN.For example, a measurement threshold is configured for the terminal.When a measurement value obtained by the terminal by measuring the cellof the SN is greater than the threshold, the terminal directly sends theuplink RRC message for the SN to the SN. Otherwise, the terminal addsthe uplink RRC message for the SN to an RRC message sent to the MN, tosend the uplink RRC message for the SN to the MN, and the MN sends theuplink RRC message for the SN to the SN.

4. It is configured that a first-type uplink RRC message for the SN isdirectly sent to the SN, and a second-type uplink RRC message for the SNis sent to the SN through the MN. The first-type and second-type uplinkRRC messages of the SN may include more than one message type, and maybe specifically configured based on a requirement, and are not limitedherein.

5. A rule that uplink is subordinate to downlink is configured. If adownlink RRC message is received on the SRB of the SN, a correspondinguplink RRC message is also sent on the SRB of the SN, that is, theterminal sends the uplink RRC message for the SN on a same path as thedownlink RRC message of the SN. Optionally, the uplink RRC message is aresponse message for the downlink RRC message, similar to that in theembodiment shown in FIG. 9. The embodiment shown in FIG. 9 may beimplemented through agreement between the terminal and a network sidewithout configuration by the MN, or may be implemented throughconfiguration by the MN.

6. An uplink RRC message for the SN does not affect the MN by default,and is directly sent on the SRB of the SN, that is, the terminaldirectly sends the uplink RRC message for the SN to the SN.Alternatively, an uplink RRC message for the SN affects the MN bydefault, and is sent to the SN through the MN, that is, the terminalsends the uplink RRC message for the SN to the SN through the MN.

Regardless of uplink or downlink, in a scenario in which the MN sends anRRC message of the SN to the SN, a tunnel is established between the MNand the SN for transmitting an RRC message sent by the terminal to theSN. For example, an SCG SRB may be indicated in an SN addition requestmessage, and an acknowledgment message returned by the SN to the MNcarries a tunnel endpoint identifier (TEID) allocated to the SCG SRB.

It should be noted that the embodiment shown in FIG. 9 or FIG. 10 may becombined with the previous embodiment, to further improve uplink RRCmessage transmission reliability.

In an LTE-NR dual connectivity scenario in which LTE is used as ananchor, if an SN works at a high frequency, a beamforming technology maybe used. A terminal may need to measure and report a beam in the SN, toselect a proper beam for the terminal. Currently, both measurementconfiguration and measurement reporting of the terminal are performed atan MN. To be specific, the MN performs measurement configuration for theterminal, and the terminal performs measurement based on the measurementconfiguration, and sends a measurement report to the MN when ameasurement event is met. Therefore, in the LTE-NR dual connectivityscenario, if the existing manner is still used, movement of the terminalbetween cells or beams of the SN needs to be controlled by the MN. Whenthe MN determines to change a cell or beam, the MN notifies theterminal, and the MN further needs to notify the SN, to implementmovement of the terminal in the SN.

It can be learned that a time required by an entire configurationprocess includes a time of air interface transmission between the MN ofthe LTE standard and the terminal and a time of interface interactionbetween the MN and the SN. Compared with a case in which configurationand interaction are directly implemented between the SN and theterminal, the existing mechanism has a longer latency. In ahigh-frequency movement scenario, it is possible that the existingmechanism cannot meet a low-latency requirement. In the foregoingembodiments, an RRC message may be directly transmitted between theterminal and the SN, that is, the SN may establish an SRB forcommunication with the terminal. In this case, the MN may configure onlyLTE measurement for the terminal, and NR measurement is configured bythe SN. If the MN and the SN both configure NR measurement for theterminal, a problem such as inconsistent configuration may be caused.The MN may also learn of information about a surrounding NR cell, toimplement switching or SCG management. To further improve mobilitymanagement efficiency, in an embodiment of this application, an MN sendsmeasurement configuration information to an SN, where the measurementconfiguration information is used to configure a condition fortriggering the SN to send, to the MN, a result of measuring a cell ofthe SN by a terminal. For example, the measurement configurationinformation is a threshold. When a measurement result in a measurementreport received by the SN is greater than or equal to the threshold, theSN sends the measurement result to the MN, so that the MN performsmobility management, for example, makes a switching decision or performsSCG management.

Referring to FIG. 11, FIG. 11 is a schematic diagram of a configurationmethod according to an embodiment of this application. As shown in FIG.11, the method is applied to a communications system, where thecommunications system includes an MN and an SN that jointly provide aservice for a terminal, measurement of a cell of the MN by the terminalis configured by the MN, measurement of a cell of the SN by the terminalis configured by the SN, and the method includes the following steps:

S1110: The MN sends measurement configuration information to the SN,where the measurement configuration information is used to configure acondition for triggering the SN to send a measurement result to the MN.

S1120: The SN receives a measurement report that is obtained bymeasuring a cell of the SN and that is sent by the terminal.

S1130: When the measurement report includes a measurement result meetingthe foregoing condition, the SN sends the measurement result to the MN.

Certainly, the SN may send all measurement results in all measurementreports to the MN, or may send only a measurement result meeting thecondition. This is not limited herein.

The measurement configuration information may include a threshold. Whena measurement result in a measurement report obtained by the SN isgreater than or equal to the threshold, the SN sends the measurementresult to the MN. That is, step S1110 may be: sending, by the MN, athreshold to the SN. Step S1130 may be: when a measurement result in themeasurement report is greater than or equal to the threshold, sending,by the SN, the measurement result to the MN. Optionally, the SN may sendall measurement results to the MN, or may send some measurement resultsto the MN. For example, a measurement value greater than or equal to thethreshold is sent to the MN. In addition, information sent by the SN mayfurther include a cell/beam identifier corresponding to the sentmeasurement result.

In addition, the SN may also configure the threshold for the terminal asa measurement threshold. Alternatively, the SN may configure, for theterminal, another measurement threshold different from the threshold.That is, the SN may configure a measurement event for the terminal withreference to the threshold. For example, the SN may configure, for theterminal as a threshold of the measurement event, the threshold obtainedfrom the MN. Alternatively, the SN may configure a measurement thresholdfor the terminal by itself, without reference to the threshold.

For example, the MN is an LTE eNB, and the SN is an NR gNB. Afterinitial configuration is completed, only LTE measurement is implementedbetween the MN and the terminal, and NR measurement configuration andreporting are performed between the SN and the terminal. To enable theMN to learn of NR measurement to implement mobility management (forexample, MN switching or SN switching), the MN may obtain a requiredmeasurement result from the SN. For example, the MN may configure athreshold for the SN. The threshold may be a reference signal receivedpower (RSRP) threshold, a reference signal received quality (RSRQ)threshold, or the like. The threshold may be carried in an SNaddition/modification request message and sent to the SN. The SNreceives a measurement report reported by the terminal. The measurementreport includes a result of measuring an NR cell and/or beam, forexample, includes a measurement value such as RSRP or RSRQ of the NRcell or beam. When a result of measuring an NR cell or beam exceeds thethreshold configured by the MN, the SN sends measurement information tothe MN. The measurement information includes an identifier and ameasurement result of at least one NR cell/beam.

It should be noted that this embodiment may be combined with theprevious embodiment, to further improve terminal mobility managementefficiency.

Referring to FIG. 12, FIG. 12 is a schematic diagram of an apparatusaccording to an embodiment of this application. The apparatus 1200 isapplied to an SN in a communications system. The communications systemincludes an MN and the SN that jointly provide a service for a terminal.As shown in FIG. 12, the apparatus 1200 includes units or means forperforming steps performed by an SN in any method embodiment of theforegoing method, and all detailed descriptions about these steps areapplicable to this apparatus embodiment. For example, the apparatus 1200includes a first communications unit 1210 and a second communicationsunit 1220. The first communications unit 1210 is configured to controlcommunication between the SN and the MN, and may include a firstreceiving unit and a first sending unit that are respectively configuredto control receiving and sending. The first communications unit 1210 mayreceive and send messages through an interface (for example, an X2interface, which may also be referred to as an Xn interface) between theSN and the MN. The second communications unit 1220 is configured tocontrol communication between the SN and the terminal, and may include asecond receiving unit and a second sending unit that are respectivelyconfigured to control receiving and sending. The second communicationsunit 1220 may receive and send messages through an interface (forexample, an air interface) between the SN and the terminal. Theinterface herein is a logical concept, and a corresponding logical unitneeds to be set during implementation, to meet a protocol requirement ofa corresponding interface. A physical connection between nodes may be awireless connection, or may be a wired connection. For example, awireless connection manner may be used for a RAN node (the MN or the SN)and the terminal, and a wired connection manner may be used for the SNand the MN.

In the foregoing method embodiments, all messages or informationreceived by the SN from the MN may be received under control of thefirst communications unit 1210, and all messages or information sent bythe SN to the MN may be sent under control of the first communicationsunit 1210. All messages or information received by the SN from theterminal may be received under control of the second communications unit1220, and all messages or information sent by the SN to the terminal maybe sent under control of the second communications unit 1220.

For example, the foregoing apparatus 1200 may be a configurationapparatus, and further include a generation unit 1230, configured togenerate configuration information for an SRB, where the SRB is used totransmit an RRC message between the SN and the terminal. The firstcommunications unit 1210 is configured to send the configurationinformation for the SRB to the MN, so that the configuration informationfor the SRB is sent to the terminal through the MN. When the terminalsends a configuration result to the SN through the MN, the firstcommunications unit 1210 is configured to receive a result ofconfiguring the SRB by the terminal by using the configurationinformation for the SRB. When the terminal directly sends aconfiguration result to the SN, the second communications unit 1220 isconfigured to receive a result of configuring the SRB by the terminal byusing the configuration information for the SRB.

For descriptions about cases in which the generation unit 1230 generatesthe configuration information for the SRB, and forms and content of theconfiguration information for the SRB, refer to the foregoingembodiments, and details are not described herein again. In addition,for details about other sent or received messages or information, referto the foregoing method embodiments, and details are not describedherein again. Moreover, for content or forms of the sent or receivedmessages or information, also refer to the foregoing method embodiments.

Optionally, the first communications unit 1210 is further configured toreceive security information used for the SRB of the SN from the MN. Inthis case, the apparatus 1200 may further include a security processingunit 1240, configured to: before the configuration information for theSRB is sent to the MN, perform security processing on the configurationinformation for the SRB of the SN by using the security information.

Optionally, the first communications unit 1210 is further configured toreceive a key group from the master node. In this case, the apparatus1200 may further include a selection unit 1250, configured to select akey from the key group when the SN updates a key.

For another example, the foregoing apparatus 1200 may be anotherconfiguration apparatus. The first communications unit 1210 isconfigured to receive measurement configuration information from the MN,where the measurement configuration information is used to configure acondition for triggering the SN to send a measurement result to the MN.The second communications unit 1220 is configured to receive, from theterminal, a measurement report obtained by the terminal by measuring acell of the SN. When the measurement report includes a measurementresult meeting the foregoing condition, the first communications unit1210 is configured to send the measurement result to the MN.

It should be understood that division of the units of the foregoingapparatus is merely division of logical functions. During actualimplementation, all or some of the units may be integrated into aphysical entity, or may be physically separated. Moreover, these unitsmay be all implemented in a form of software invoked by a processingelement, or may be all implemented by hardware, or some units may beimplemented in a form of software invoked by a processing element, andsome units may be implemented by hardware. For example, duringimplementation, the first communications unit 1210 may be a separatelydisposed processing element, or may be integrated into a chip of the SN.Alternatively, the first communications unit 1210 may be stored in amemory of the SN as a program and invoked by a processing element of theSN to perform a function of the unit. Implementation of other units issimilar thereto. In addition, all or some of these units may beintegrated or separately implemented. The processing element herein maybe an integrated circuit having a signal processing capability. In animplementation process, the steps of the foregoing method or theforegoing units may be completed by using a hardware-integrated logiccircuit in a processor element or instructions in a form of software. Inaddition, the foregoing first communications unit is a communicationcontrol unit, and may receive information sent by the MN or sendinformation to the MN through a connection medium, for example, anoptical fiber, between the SN and the MN. The foregoing secondcommunications unit is a communication control unit, and may receiveinformation sent by the terminal or send information to the terminalthrough a receive apparatus, for example, an antenna and a radiofrequency apparatus, of the SN.

For example, the foregoing units may be configured as one or moreintegrated circuits for implementing the foregoing method, for example,one or more application-specific integrated circuits (ASIC), or one ormore microprocessors (digital signal processor, DSP), or one or morefield-programmable gate arrays (FPGA). For another example, when a unitabove is implemented in a form of a program scheduled by a processingelement, the processing element may be a general-purpose processor, forexample, a central processing unit (CPU) or another processor that caninvoke a program. For another example, these units may be integrated,and implemented in a system-on-a-chip (SOC) form.

Referring to FIG. 13, FIG. 13 is a schematic diagram of an apparatusaccording to an embodiment of this application. The apparatus 1300 isapplied to an MN in a communications system. The communications systemincludes the MN and an SN that jointly provide a service for a terminal.As shown in FIG. 13, the apparatus 1300 includes units or means forperforming steps performed by an MN in any method embodiment of theforegoing method, and all detailed descriptions about these steps areapplicable to this apparatus embodiment. The apparatus 1300 includes afirst receiving unit 1310, a first sending unit 1320, a second receivingunit 1330, and a second sending unit 1340. The first receiving unit 1310and the first sending unit 1320 may be referred to as a firstcommunications unit, configured to control communication between the MNand the SN; and may receive and send messages through an interface (forexample, an X2 interface, which may also be referred to as an Xninterface) between the MN and the SN. The second receiving unit 1330 andthe second sending unit 1340 may be referred to as a secondcommunications unit, configured to control communication between the MNand the terminal; and may receive and send messages through an interface(for example, an air interface) between the MN and the terminal. Theinterface herein is a logical concept, and a corresponding logical unitneeds to be set during implementation, to meet a protocol requirement ofa corresponding interface. A physical connection between nodes may be awireless connection, or may be a wired connection. For example, awireless connection manner may be used for a RAN node (the MN or the SN)and the terminal, and a wired connection manner may be used for the MNand the SN.

In the foregoing method embodiments, all messages or informationreceived by the MN from the SN may be received under control of thefirst receiving unit 1310, and all messages or information sent by theMN to the SN may be sent under control of the first sending unit 1320.All messages or information received by the MN from the terminal may bereceived under control of the second receiving unit 1330, and allmessages or information sent by the MN to the terminal may be sent undercontrol of the second sending unit 1340.

For example, the first receiving unit 1310 is configured to receiveconfiguration information for an SRB from the SN, where the SRB is usedto transmit an RRC message between the SN and the terminal. The“transmit” herein means directly transmitting without forwarding by theMN. The second sending unit 1340 is configured to send the configurationinformation for the SRB to the terminal. The second receiving unit 1330is configured to receive a result of configuring the SRB by the terminalby using the configuration information for the SRB. The first sendingunit 1320 is configured to send the configuration result to the SN. Fordetails about other sent or received messages or information, refer tothe foregoing method embodiments, and details are not described hereinagain. Moreover, for content or forms of the sent or received messagesor information, also refer to the foregoing method embodiments.

For another example, the foregoing apparatus is an RRC messagetransmission apparatus, and further includes a generation unit 1350,configured to generate uplink RRC configuration information of the SN,or the first receiving unit 1310 is configured to receive uplink RRCconfiguration information from the SN. The uplink RRC configurationinformation is used to configure a manner in which the terminal sends anuplink RRC message for the SN. The second sending unit 1340 isconfigured to send the uplink RRC configuration information to theterminal, so that the terminal sends the uplink RRC message based on theuplink RRC configuration information. The sending manner is the same asthat in the foregoing embodiments, and details are not described hereinagain.

For another example, the foregoing apparatus is a configurationapparatus. The first sending unit 1320 is configured to send measurementconfiguration information to the SN, where the measurement configurationinformation is used to configure a condition for triggering the SN tosend a measurement result to the MN. The first receiving unit 1310receives a measurement result meeting the foregoing condition from theSN, where the measurement result is obtained by the terminal bymeasuring a cell of the SN and reported to the SN.

It should be understood that division of the units of the foregoingapparatus is merely division of logical functions. During actualimplementation, all or some of the units may be integrated into aphysical entity, or may be physically separated. Moreover, these unitsmay be all implemented in a form of software invoked by a processingelement, or may be all implemented by hardware, or some units may beimplemented in a form of software invoked by a processing element, andsome units may be implemented by hardware. For example, duringimplementation, the first receiving unit 1310 may be a separatelydisposed processing element, or may be integrated into a chip of the MN.Alternatively, the first receiving unit 1310 may be stored in a memoryof the MN as a program and invoked by a processing element of the MN toperform a function of the unit. Implementation of other units is similarthereto. In addition, all or some of these units may be integrated orseparately implemented. The processing element herein may be anintegrated circuit having a signal processing capability. In animplementation process, the steps of the foregoing method or theforegoing units may be completed by using a hardware-integrated logiccircuit in a processor element or instructions in a form of software. Inaddition, the foregoing first receiving unit is a receiving control unitand may receive, through a receive apparatus, for example, an antennaand a radio frequency apparatus, of the MN, information sent by theterminal. The foregoing first sending unit is a sending control unit andmay send information to the terminal through a transmit apparatus, forexample, an antenna and a radio frequency apparatus, of the MN. Theforegoing second receiving unit is a receiving control unit and mayreceive, through a connection medium, for example, an optical fiber,between the MN and the SN, information sent by the SN. The foregoingsecond sending unit is a sending control unit and may send informationto the SN through a connection medium, for example, an optical fiber,between the MN and the SN.

For example, the foregoing units may be configured as one or moreintegrated circuits for implementing the foregoing method, for example,one or more application-specific integrated circuits (ASIC), or one ormore microprocessors (digital signal processor, DSP), or one or morefield-programmable gate arrays (FPGA). For another example, when a unitabove is implemented in a form of a program scheduled by a processingelement, the processing element may be a general-purpose processor, forexample, a central processing unit (CPU) or another processor that caninvoke a program. For another example, these units may be integrated,and implemented in a system-on-a-chip (SOC) form.

Referring to FIG. 14, FIG. 14 is a schematic diagram of an apparatusaccording to an embodiment of this application. The apparatus 1400 isapplied to a terminal in a communications system. The communicationssystem includes an MN and an SN that jointly provide a service for theterminal. As shown in FIG. 14, the apparatus 1400 includes units ormeans for performing steps performed by a terminal in any methodembodiment of the foregoing method, and all detailed descriptions aboutthese steps are applicable to this apparatus embodiment. The apparatusincludes a receiving unit 1410 and a sending unit 1420. The receivingunit 1410 and the sending unit 1420 are configured to controlcommunication with a RAN node (for example, the MN or the SN), and mayreceive and send messages through an interface (for example, an airinterface) between the terminal and the RAN node. The interface hereinis a logical concept, and a corresponding logical unit needs to be setduring implementation, to meet a protocol requirement of a correspondinginterface. A physical connection between nodes may be a wirelessconnection.

In the foregoing method embodiments, all messages or informationreceived by the terminal from the MN or the SN may be received undercontrol of the receiving unit 1410, and all messages or information sentby the terminal to the MN or the SN may be sent under control of thesending unit 1420.

For example, the foregoing apparatus 1400 is a configuration apparatus,and further includes a configuration unit 1430. The receiving unit 1410is configured to receive configuration information for an SRB of the SNfrom the MN, where the SRB is used to transmit an RRC message betweenthe SN and the terminal. The “transmit” herein means directlytransmitting without forwarding by the MN. The configuration unit 1430is configured to configure the SRB by using the configurationinformation for the SRB. The sending unit 1420 is configured to send aresult of configuring the SRB. For details about other sent or receivedmessages or information, refer to the foregoing method embodiments, anddetails are not described herein again. Moreover, for content or formsof the sent or received messages or information, also refer to theforegoing method embodiments.

In addition, the configuration unit 1430 may be further configured toperform other RRC configuration. For example, after SRB configuration iscompleted, the receiving unit 1410 may receive an RRC connectionreconfiguration message from the SN. In this case, the configurationunit 1430 may perform reconfiguration corresponding to the RRCconnection reconfiguration message. Moreover, when reconfigurationfails, the configuration unit 1430 may restore configuration before theRRC connection reconfiguration message is received.

For another example, the foregoing apparatus is an RRC messagetransmission apparatus. The receiving unit 1410 is configured to receivea downlink RRC message of the SN, where the downlink RRC message isreceived by the MN from the SN and sent to the terminal, or the downlinkRRC message is sent by the SN to the terminal. The sending unit 1420 isconfigured to send an uplink RRC message, where the uplink RRC messageis a response message for the downlink RRC message, and a path on whichthe sending unit 1420 sends the uplink RRC message is the same as a pathon which the receiving unit 1410 receives the downlink RRC message. Thatis, when the downlink RRC message is received by the MN from the SN andsent to the terminal, the uplink RRC message is sent by the terminal tothe MN and sent by the MN to the SN. Alternatively, when the downlinkRRC message is sent by the SN to the terminal, the uplink RRC message issent by the terminal to the SN.

For another example, the foregoing apparatus is an RRC messagetransmission apparatus. The receiving unit 1410 is configured to receiveuplink RRC configuration information of the SN from the MN, where theuplink RRC configuration information is used to configure a manner inwhich the terminal sends an uplink RRC message for the SN. The sendingunit 1420 is configured to send the uplink RRC message for the SN basedon the uplink RRC configuration information. The sending manner is thesame as that in the foregoing embodiments, and details are not describedherein again.

It should be understood that division of the units of the foregoingapparatus is merely division of logical functions. During actualimplementation, all or some of the units may be integrated into aphysical entity, or may be physically separated. Moreover, these unitsmay be all implemented in a form of software invoked by a processingelement, or may be all implemented by hardware, or some units may beimplemented in a form of software invoked by a processing element, andsome units may be implemented by hardware. For example, duringimplementation, the receiving unit 1410 may be a separately disposedprocessing element, or may be integrated into a chip of the terminal.Alternatively, the receiving unit 1410 may be stored in a memory of theterminal as a program and invoked by a processing element of theterminal to perform a function of the unit. Implementation of otherunits is similar thereto. In addition, all or some of these units may beintegrated or separately implemented. The processing element herein maybe an integrated circuit having a signal processing capability. In animplementation process, the steps of the foregoing method or theforegoing units may be completed by using a hardware-integrated logiccircuit in a processor element or instructions in a form of software. Inaddition, the receiving unit is a receiving control unit and mayreceive, through a receive apparatus, for example, an antenna and aradio frequency apparatus, of the terminal, information sent by the MNor the SN. The sending unit is a sending control unit and may sendinformation to the MN or the SN through a transmit apparatus, forexample, an antenna and a radio frequency apparatus, of the terminal.

For example, the foregoing units may be configured as one or moreintegrated circuits for implementing the foregoing method, for example,one or more application-specific integrated circuits (ASIC), or one ormore microprocessors (digital signal processor, DSP), or one or morefield-programmable gate arrays (FPGA). For another example, when a unitabove is implemented in a form of a program scheduled by a processingelement, the processing element may be a general-purpose processor, forexample, a central processing unit CPU) or another processor that caninvoke a program. For another example, these units may be integrated,and implemented in a system-on-a-chip (SOC) form.

Referring to FIG. 15, FIG. 15 is a schematic structural diagram of a RANnode according to an embodiment of this application. The RAN node may bethe SN or the MN in the foregoing embodiment, configured to implementoperations of the SN or the MN in the foregoing embodiment. As shown inFIG. 15, the RAN node includes: an antenna 1510, a radio frequencyapparatus 1520, and a baseband apparatus 1530. The antenna 1510 isconnected to the radio frequency apparatus 1520. In an uplink direction,the radio frequency apparatus 1520 receives, through the antenna 1510,information sent by a terminal, and sends the information sent by theterminal to the baseband apparatus 1530 for processing. In a downlinkdirection, the baseband apparatus 1530 processes information of theterminal, and sends the information of the terminal to the radiofrequency apparatus 1520, and the radio frequency apparatus 1520processes the information of the terminal, and then sends theinformation of the terminal to the terminal through the antenna 1510.Communication between RAN nodes, for example, between an MN and an SN,may be performed through a transmission medium. The transmission mediummay be a wired medium, for example, an optical fiber; or may be awireless medium.

The foregoing configuration apparatus applied to the SN or the MN may belocated in the baseband apparatus 1530. In an implementation, the unitsshown in FIG. 12 or FIG. 13 are implemented in a form of a programscheduled by a processing element. For example, the baseband apparatus1530 includes a processing element 1531 and a storage element 1532. Theprocessing element 1531 invokes a program stored in the storage element1532, to perform a method performed by the SN or the MN in the foregoingmethod embodiments. In addition, the baseband apparatus 1530 may furtherinclude an interface 1533, configured to exchange information with theradio frequency apparatus 1520. The interface is, for example, a commonpublic radio interface (CPRI).

In another implementation, the units shown in FIG. 12 or FIG. 13 may beconfigured as one or more processing elements for implementing a methodperformed by the SN or the MN. These processing elements are disposed onthe baseband apparatus 1530. The processing elements herein may be anintegrated circuit, for example, one or more ASICs, or one or more DSPs,or one or more FPGAs. These integrated circuits may be integrated toform a chip.

For example, the units shown in FIG. 12 or FIG. 13 may be integrated,and implemented in a system-on-a-chip (SOC) form. For example, thebaseband apparatus 1530 includes an SOC chip, configured to implementthe foregoing method. The chip may be integrated with the processingelement 1531 and the storage element 1532, and the processing element1531 invokes a program stored in the storage element 1532 to implementthe foregoing method performed by the SN or the MN or functions of theunits shown in FIG. 12 or FIG. 13. Alternatively, the chip may beintegrated with at least one integrated circuit, to implement the methodperformed by the SN or the MN or functions of the units shown in FIG. 12or FIG. 13. Alternatively, the foregoing implementations may becombined, where functions of some units are implemented by theprocessing element by invoking a program, and functions of some unitsare implemented by an integrated circuit.

Regardless of the manners used, the foregoing configuration apparatusapplied to the SN or the MN includes at least one processing element anda storage element, where the at least one processing element isconfigured to perform the method that is performed by the SN or the MNand provided in the foregoing method embodiments. The processing elementmay perform, in a first manner, that is, by running a program stored inthe storage element, some or all steps performed by the SN or the MN inthe foregoing method embodiments; or may perform, in a second manner,that is, by using a hardware-integrated logic circuit in a processorelement and instructions, some or all steps performed by the SN or theMN in the foregoing method embodiments; or certainly, may perform, bycombining the first manner and the second manner, the method performedby the SN or the MN in the foregoing method embodiments.

The processing element herein is the same as that in the foregoingdescription, and may be a general-purpose processor, for example, acentral processing unit CPU), or may be configured as one or moreintegrated circuits for implementing the foregoing method, for example,one or more application-specific integrated circuits (ASIC), or one ormore microprocessors (digital signal processor, DSP), or one or morefield-programmable gate arrays (FPGA).

The storage element may be a memory, or may be a collective name for aplurality of storage elements.

Referring to FIG. 16, FIG. 16 is a schematic structural diagram of aterminal according to an embodiment of this application. The terminalmay be the terminal in the foregoing embodiment, configured to implementoperations of the terminal in the foregoing embodiment. As shown in FIG.16, the terminal includes: a processing element 1610, a storage element1620, and a transceiver element 1630. The transceiver element 1630 maybe connected to an antenna. In a downlink direction, the transceiverelement 1630 receives, through the antenna, information sent by a basestation, and sends the information to the processing element 1610 forprocessing. In an uplink direction, the processing element 1610processes data of the terminal, and sends the data of the terminal tothe base station through the transceiver element 1630.

The storage element 1620 is configured to store a program forimplementing the foregoing method embodiment. The processing element1610 invokes the program, to perform an operation in the foregoingmethod embodiment.

In another implementation, the units shown in FIG. 14 may be configuredas one or more processing elements for implementing a method performedby the foregoing terminal. These processing elements are disposed on acircuit board of the terminal. The processing elements herein may be anintegrated circuit, for example, one or more ASICs, or one or more DSPs,or one or more FPGAs. These integrated circuits may be integrated toform a chip.

For example, the units shown in FIG. 14 may be integrated, andimplemented in a system-on-a-chip (SOC) form. For example, the terminalincludes an SOC chip, configured to implement the foregoing method. Thechip may be integrated with the processing element 1610 and the storageelement 1620, and the processing element 1610 invokes the program storedin the storage element 1620 to implement the foregoing method orfunctions of the units shown in FIG. 14. Alternatively, the chip may beintegrated with at least one integrated circuit, to implement theforegoing method or functions of the units shown in FIG. 14.Alternatively, the foregoing implementations may be combined, wherefunctions of some units are implemented by the processing element byinvoking a program, and functions of some units are implemented by anintegrated circuit.

Regardless of the manners used, the foregoing configuration apparatusincludes at least one processing element and a storage element, wherethe at least one processing element is configured to perform the methodprovided in the foregoing method embodiments. The processing element mayperform, in a first manner, that is, by running a program stored in thestorage element, some or all steps in the foregoing method embodiments;or may perform, in a second manner, that is, by using ahardware-integrated logic circuit in a processor element andinstructions, some or all steps in the foregoing method embodiments; orcertainly, may perform, by combining the first manner and the secondmanner, the method provided in the foregoing method embodiments.

The processing element herein is the same as that in the foregoingdescription, and may be a general-purpose processing element, forexample, a central processing unit (CPU), or may be configured as one ormore integrated circuits for implementing the foregoing method, forexample, one or more application-specific integrated circuits (ASIC), orone or more microprocessors (digital signal processor, DSP), or one ormore field-programmable gate arrays (FPGA).

The storage element may be a memory, or may be a collective name for aplurality of storage elements.

A person of ordinary skill in the art may understand that all or some ofthe steps of the method embodiments may be implemented by a programinstructing relevant hardware. The program may be stored in a computerreadable storage medium. When the program is run, the steps of themethod embodiments are performed. The storage medium includes: variousmedia that can store program code, such as a ROM, a RAM, a magneticdisk, or an optical disc.

What is claimed is:
 1. A configuration method, comprising: receiving, bya terminal, configuration information for a signaling radio bearer (SRB)of a secondary node from a master node, wherein the SRB is used to carrya radio resource control (RRC) message between the secondary node andthe terminal; and configuring, by the terminal, the SRB by using theconfiguration information for the SRB; and sending, by the terminal, aresult of configuring the SRB.
 2. The method according to claim 1,wherein the sending, by the terminal, a result of configuring the SRBcomprises: sending, by the terminal, the result to the secondary nodedirectly; or sending, by the terminal, the result to the secondary nodethrough the master node.
 3. The method according to claim 1, wherein theconfiguration information for the SRB comprises: an SRB identifier, aradio link control (RLC) layer configuration of the SRB, a logicalchannel configuration, and an SRB security parameter.
 4. The methodaccording to claim 1, further comprising: receiving, by the terminal, acount value from the secondary node, and updating a key based on thecount value.
 5. The method according to claim 1, further comprising:receiving, by the terminal, an RRC connection reconfiguration messagefrom the secondary node; and when the terminal fails to performreconfiguration corresponding to the RRC connection reconfigurationmessage, working, by the terminal, based on configuration before the RRCconnection reconfiguration message is received.
 6. The method accordingto claim 5, wherein the terminal does not trigger RRC connectionre-establishment.
 7. The method according to claim 5, furthercomprising: sending, by the terminal, a configuration failurenotification to the master node.
 8. The method according to claim 1,further comprising: receiving, by the terminal, a downlink RRC messageof the secondary node, wherein the downlink RRC message is received bythe master node from the secondary node and sent to the terminal, or thedownlink RRC message is sent by the secondary node to the terminal; andsending, by the terminal, an uplink RRC message, wherein the uplink RRCmessage is a response message for the downlink RRC message, and a pathon which the terminal sends the uplink RRC message is the same as a pathon which the terminal receives the downlink RRC message.
 9. Aconfiguration apparatus, comprising at least one processor and a memorycoupled to the at least one processor, the at least one processor beingconfigured to: receive configuration information for a signaling radiobearer (SRB) of a secondary node from a master node, wherein the SRB isused to carry a radio resource control (RRC) message between thesecondary node and the apparatus; and configure the SRB by using theconfiguration information for the SRB; and send a result of configuringthe SRB.
 10. The apparatus according to claim 9, wherein the at leastone processor is configured to send the result to the secondary nodethrough the master node.
 11. The apparatus according to claim 9, whereinthe configuration information for the SRB comprises: an SRB identifier,a radio link control (RLC) layer configuration of the SRB, a logicalchannel configuration, and an SRB security parameter.
 12. The apparatusaccording to claim 9, the at least one processor is further configuredto: receive a count value from the secondary node; and update a keybased on the count value.
 13. The apparatus according to claim 9, the atleast one processor is further configured to: receive an RRC connectionreconfiguration message from the secondary node; and work based onconfiguration before the RRC connection reconfiguration message isreceived when reconfiguration corresponding to the RRC connectionreconfiguration message is failed.
 14. The apparatus according to claim13, wherein RRC connection re-establishment is not triggered.
 15. Theapparatus according to claim 13, the at least one processor is furtherconfigured to: send a configuration failure notification to the masternode.
 16. The apparatus according to claim 9, the at least one processoris further configured to: receive a downlink RRC message of thesecondary node, wherein the downlink RRC message is received by themaster node from the secondary node and sent to the apparatus, or thedownlink RRC message is sent by the secondary node to the apparatus; andsend an uplink RRC message, wherein the uplink RRC message is a responsemessage for the downlink RRC message, and a path on which the apparatussends the uplink RRC message is the same as a path on which theapparatus receives the downlink RRC message.
 17. A non-transitorycomputer-readable storage medium, comprising a program, wherein whenbeing executed by a processor, the following steps are performed:receiving configuration information for a signaling radio bearer (SRB)of a secondary node from a master node, wherein the SRB is used to carrya radio resource control (RRC) message between the secondary node andthe apparatus; and configuring the SRB by using the configurationinformation for the SRB; and sending a result of configuring the SRB.18. The non-transitory computer-readable storage medium according toclaim 17, wherein the result is sent to the secondary node through themaster node.
 19. The non-transitory computer-readable storage mediumaccording to claim 17, wherein the configuration information for the SRBcomprises: an SRB identifier, a radio link control (RLC) layerconfiguration of the SRB, a logical channel configuration, and an SRBsecurity parameter.
 20. The non-transitory computer-readable storagemedium according to claim 17, wherein when the program is executed bythe processor, the following steps are further performed: receiving anRRC connection reconfiguration message from the secondary node; andworking based on configuration before the RRC connection reconfigurationmessage is received when reconfiguration corresponding to the RRCconnection reconfiguration message is failed.